So, you managed to raise a nice fortune, let's say about 10-15 million/day and you want to improve your fortune.

Here are some tips.

As you can see MonopolyCityStreets have a list of buildings available. Everyone can use whatever building they want. I personally prefer Cubic Quarters building, which is evaluated to 2 Million and has a daily revenue of 950.000.

The reason why I choose this building is because of the small amount of space needed. You can put these buildings very close to each other. You can sell them next day without loosing any money.

My strategy was to put many buildings like this on all my streets and wait for the daily rent. Every money earned from my rent, were invested in these buildings. I managed to get to 400 buildings like this/street and had 5 streets like this.

As a medium strategy is very good but you need to be very careful about the fact that if you'll be at level 5 for example, you'll be on risk of getting chance cards which will give you high taxes.